President Nixon today announced what amounted to a partial ceasefire in Vietnam and the news was received in Washington as a clear signal that the signing of a full ceasefire agreement is now imminent.

As from 10 o'clock Washington time this morning, all bombing, shelling, and mining of North Vietnam came to an end. The President's press spokesman made his announcement shortly before 11 am. He said that it was a "unilateral" decision by Mr Nixon "based on his assessment of the negotiations as they stand right now."

Nobody quite dared to say that "peace is at hand," but Administration sources in Washington, although claiming to have no knowledge of what had been agreed in Paris, jumped to the conclusion that the President would not have taken such a dramatic step, only five days before his inauguration, unless he had been confident that this time it really was in the bag.

The announcement followed a spate of rumours to the effect that Dr Kissinger and Mr Le Duc Tho had reached agreement in Paris last week and that President Thieu was now ready to acquiesce.

According to the CBS chief correspondent, Richard Wagner, the revised agreement gives "temporary" recognition to the demilitarised zone. This may well be the face-saving device which turned the trick in Paris. Such wording would enable President Thieu to go on regarding the DMZ as a frontier while Hanoi could go on contending that Vietnam is a single country temporarily divided.

The terms of the agreement will be studied carefully by Mr Nixon's critics to see if they are measurably better than could have been obtained at the end of October.

The President will ­presumably claim that the 12-day bombing of the North Vietnamese cities at the end of the year forced Hanoi to enter into a "just and lasting peace."

The Pentagon said today that ­bombing in South Vietnam, Laos, and Cambodia would continue "as ­necessary." In the past the US has resumed bombing of North Vietnamese targets in response to threats against or attacks on its reconnaissance flights.

Dr Kissinger is expected to return to Paris this week. Whether or not a ceasefire agreement is initialled in time for the inaugural celebrations, Mr Nixon will feel entitled to claim that he has discharged his pledge to end the American war in Vietnam during his first term of office.